1. Technical Field
The present invention relates to throttle valves and throttles using such throttle valves. For example, the present invention relates to throttles that may be suitably utilized to adjust the flow of intake air into internal combustion engines.
2. Description of the Related Art
A known throttle is described in Japanese Laid-Open Patent Publication No. 9-4473 and the known throttle has been reproduced herein in FIGS. 6 to 8. FIG. 6 shows a schematic side view of the throttle, FIG. 7 is a side cross-sectional view of the throttle, and FIG. 8 is an enlarged view of a portion of FIG. 7. As shown in FIG. 7, a bore 11b is formed within a throttle body 11 in order to define an intake air channel 11a. The intake air channel 11a communicates with an internal combustion engine in order to supply a flow of air to the internal combustion engine. A throttle shaft 13 is rotatably supported on the throttle body 11 so as to extend across the intake air channel 11a. A throttle valve 15 is configured as a substantially circular disk-shaped butterfly valve and is affixed to the throttle shaft 13. Therefore, the throttle valve 15 can be rotated to open and close the intake air channel 11a. In FIGS. 6 to 8, the throttle valve 15 is shown in the fully closed position.
Referring to FIG. 6, a stopper 12 is mounted on the throttle body 11 in a position outside of the intake air channel 11. A lever 14 is affixed to the throttle shaft 13 and is designed to contact the stopper 12 when the throttle valve 15 is in the fully closed position. Although not shown in the drawings, the lever 14 is connected to an accelerator via a wire. In addition, the throttle shaft 13 is biased by a spring (not shown) in the closing direction (clockwise direction as viewed in the drawings) of the throttle valve 15. As shown in FIG. 6, when the lever 14 contacts the stopper 12 in the fully closed position of the throttle valve 15, the throttle valve 15 is positioned perpendicular to an axial line or longitudinal axis L1 of the bore 11b (see FIG. 7).
Referring to FIG. 7, a bypass channel 11c is defined within the throttle body 11 and an orifice 16 is disposed within the bypass channel 11c. Therefore, the total amount of air that flows through the intake air channel 11a when the throttle valve 15 is disposed in the fully closed position (i.e., the amount of air that flows through the intake air channel 11a when the engine is idling) can be adjusted by changing the position of orifice 16 with respect to the bypass channel 11c. Thus, the amount of air that flows when the engine is idling will be the sum of the amount of air flow through a clearance S (which clearance S is defined between an inner wall of the bore 11b and the throttle valve 15 as shown in FIG. 8) and the amount of air flow through the bypass channel 11c. 